Electric heater



(No Model.) s Sheets-Sheet 2. L. GUTMANN. ELEGTRIG HEATER.

Patented Jan. 26, 1892.

jnye zivr waf zesses LUDVWQ Q N/ wig WMOL UNITED STATEs PATENT OFFICE.

LUDW'IG GUTMANN, OF PITTSBURG, PENNSYLVANIA:

ELECTRIC HEATER.

SPECIFICATION forming part of Letters Patent No. 467,538, dated January26, 1892. Application filed November 12, 1890. Serial No. 371,155. (Nomodel.)

.To aZZ whom it may concern.-

Be it known that I,LU.DWIG GUTMANN, a subject of the Emperor of Germany,and a resident of Pittsburg, county of Allegheny, and State ofPennsylvania, have invented certain new and useful Improvements inElectric Heaters, (Case 49,) of which the following is a specification.

'21 special form of a grate.

My invention has for its purpose to provide an apparatus to be operatedby the direct application of continuous, pulsating, alternating, orintermittent electric currents to an electric or magnetic conductor,which in turn by direct radiation or by the magnetic field establishedis used forpractical purposes.

In the accompanying drawings, Figures 1 and 2 show single forms ofelectric heaters in perspective. Figs. 3 3 showin section, 3 inelevation, 3 in plan and a modification of Fig. 2 for a grate orradiator for chimneys. Fig. 4. shows different forms of grates in planin an electric circuit. Figs. 5 and 7 show in section and Fig. 8 inperspective difierent constructions of a compartment forming part of astove. Fig. 6 shows. an insulating-piece for supporting theheating-conductor in perspective. Fig. 9 shows a system in diagram ofregulation. Fig. 10 is a perspective view of Fig. 11 shows a modifiedconstruction of support for the heating-conductor in perspective. Fig.12 is partially a diagram of the grate shown in Fig. 10. Figs. 13 and 13show different ways in diagram and perspective of winding theheating-conductors, especially when used with alternating orintermittent currents. Fig. 14 represents the invention in perspectivein its complete state. Fig.-15 is a sectional view of Fig. 14. Fig. 16shows details of Fig. 14. Fig. 1 shows the simplest, .butnot thepreferred, construction of my invention. A is preferably a metallicsh'ell, box, or receptacle of any suitable material-such as cast orsheet iron, copper, steel, &c.-preferably closed on all sides, except atthe front or door B, which side is hinged to the remaining box or shellto enable it to be opened or closed at will. 0 are insulating andfire-proof corner-pieces, such as asbestos, fire-clay, 850., aroundwhich the conductors are wound spirally and whose ends are attached tothe binding-posts F for conveniently inclosing or connecting theapparatus in circuit with a suitable generator.

I E are stands or feet to prevent the box from resting on the bareconducting-wires. The wire B may be either iron, steel, copper, Germansilver, brass, aluminium, or any other metal, and is of such a size thatthe current which is used for operating the device will cause theconductor to become heated, the heat being directly transmitted to thebox A, which in turn tends to raise the temperato re of all articlesplaced inside it. It is evident that the apparatus in this exposed formis uneconomical on account of the great amount of waste radiation thatwould take place.

Fig. 2 shows a modification of Fig. 1. In this case the box A is similarto that in Fig. 1, except that the bottom plate is replaced by a grateor perforated plate G, or else it,

may consist of a number of thin fiat strips interlaced with one another.The winding D is removed from the box in Fig. 2 and placed underneaththe box in a fire-proof hollowed or solid block or box H, which isprovided with grooves of spiral or othersuitable form,in which thewinding D is embedded and supported. Its ends are conducted to the twobinding-posts F on one side of the block H, which may consist of brick,fireclay, earthenware, china, or other suitable material. I

In Fig. 2 the box A is shown with the door 13 open and elevated abovetheblock H, so as to enable the winding D to be visibleand its positionwith regard to the box or oven A represented. The advantages of thisdisposition are apparent-namely, by placing the condoctor in a badheat-conductor little power is lost. The heat generated is reflected andradiated, so as to act on the box A above it. The nonconducting block Hserves as a screen from the outside atmosphere and as a reflectiontoward the oven A. The perforations of the bottom plate G permit an easyheating of the air inside the box while this air is retained therein, asthe other sides of the oven A are closed.

Fig. 3 shows a cross-section of block H of Fig. 2. It maybe made of anynon-conductor that can withstand the heat to which it is exposed. As anexample, I may mention earthenware or fire brick. To prevent theconductor from leaving its place, a cleat 11' may be applied, asindicated by dotted lines.

In Figs. 2 and 3 the heatingconductor D is shown to consist of but onelayer. Figs. 3, 3", and 3 show a modification in which several layersmay be superposed without touching one another and without needing thecleat 1 1'. (Indicated in Fig. 3.) Fig. 3 gives a top view of theheater, showing several layers of conductor D wound or mounted on blockH. Fig. 3 gives a front view showing the terminals F of theheating-conductor D, as in Fig. 2; but besides these a number of holesare provided for the purpose of retaining other layers of conductor Dand to enable the block to be placed in any convenient position withoutallowing the conductor D or any convolutions thereof to becomemisplaced. This is clearly shown in Fig. 3 which represents a section ofFig. 3 or Fig. 3". In this case the block II is provided with a frame orextension I which leaves a central cavity above the block II. The frameor extension H is provided with several rows of holes .2 for retainingheating-conductors D. It will be easily understood that nearly all theheat caused by the conductor D, Fig. 3, will be reflected by the blockII and the frame II". This form may be adapted for cooking purposes,instead of the simple form shown in Figs. 2 and 3, or may also be usedsimply as a radiator in chimneys or firesides, where it may be placed invertical or, preferably, in an inclined position, so as to reflect theheat properly into the room. The frame Il may be in one piece with blockII, and consists, also, of a non-conductor, orit may be mounted on ablock II and consist of a conductor or a non-conductor of heat orelectricity. The block II may consist of the same conducting ornon-conducting material, the vital point in construction being that theholes .2', supporting the heating-wire, should be in a nonconductingmaterial. If, therefore, the frame II or the whole frame or box II IIwould be made of metal, the perforations in the frame would have tocontain non-conducting bushings, as shown in Fig. 10, adapted to retainthe wire D.

Fig. t shows two diagrams of a grate G and the heating-conductor D,placed below either in spiral or zigzag form and provided with suitableterminals F for their introduction in circuit with the generator I inmultiple are with one'another.

Fig. 5 shows a modification over Figs. 1 and 2 and is a vertical sectionthrough the modi- .fied heater. In Fig. 5 the heating-wire is mountedinternally and not externally, as in Fig. 1. The receptacle A, which isused to support cooking utensils, may consist of any suitable material.It is provided with perfo rat-ions 0c in the various sides to allow theheat generated by the surrounding conductor D to penetrate quickly tothe interior. 13y placing the conductor D in the interior of the shellor box A, which may consist of sheet or cast iron or other suitablematerial, the heat remains concentrated around the support A, and therecan be but little waste. For commercial reasons, the support A may bemade of metal. As shown in Fig. 5, to prevent the support from coming incontact with the con- .duetor D the separating insulating anglepieces 0are interposed, which may have the form shown in Fig. (3. Thenon-conducting corner-piece K is provided with a number of notches orgrooves L for retaining the convolutions of the conductor D.

Fig. 7 shows a sectional View of an oven with two layers of conductor Din position and properly insulated from one another by insulatingcorner-pieces O. The conductor D, mounted in insulation, is a modifiedradiator, which, surrounding the support A and both inclosed by aheat-screen, as in Fig. 5, is preferably termed concentraton Fig. 8shows a method of regulation of heat. It consists of a support or boxA'that is, a receptaclethe sides of which are composed of perforatedplates formed of strips 1 while cast or sheet. metal plates N,adjustable and also removable in slides 9 are provided to completely orpartially inclose the box to regulate the intercommunication of the hotair.

The construction and support of the heatercoils D can be variedconsiderably and will depend on the shape of the apparatus or utensilsto be heated, as shown for circular vcssel in diagram in Fig. 12 andalso in Fig. 10. For boiling water (see Fig. 12) or other fluids a gratelike that of Fig. at would not be economical in combination with akettle shown in Fig. 12. In this latter case it is desirable to have asgreat a heating-surface applied near to the fluid as possible. For thisreason the winding D is mounted on the non-conducting columns Q, so thatall convolutions are placed in the same vertical plane around the kettleto form a heater of a similar shape to a portion thereof and to beadapted to closely surround it. The columns Q are provided with holesfor receiving and retaining the winding D, or else they may be providedwith recesses or grooves It, as shown in Fig. 11. To give the winding I)and columns Q stability, frames 0 are mounted on both top and bottom andare provided with suitable proj ections P,having cavities in which thecolumns arepermanently retained. These heaters are operative with anycurrentsuch as continuous, pulsating, or alternating; but it offersespecially advantages in combination with alternating or intermittentcurrents, because the ficld surrounding the heating-coils D will causesecondary currents to flow in the low-resistance and closed circuits ofthe pew forated plates or grates G and eddy-current in the plates N,which both assist in heating the receptacle. Further, if the box orreceptacleAis made of iron or other magnetic conductor the increasednumber of lines of force will not leak away, but are concentrated aroundthe box or shell,whieh constitutes an open-core magnet which maybequickly raised IIO to saturation, and in this manner hysteresis may bealso used to combine with the other;

factors to intensify the heating.

In making the cell, box, or shell A A N of magnetic material the effectmay be modified still further, as given in diagram in Fig. 13. Thisdiagram shows that the shell A has 'several separate circuits, one ofwhich D is in circuit with the terminals I of a suitable generator,while several windings D, which constitute closed secondarydemagnetizing-circuits, surround the common magnet core or shell A.

It is well to state at this point that any of the forms or modificationsmentioned may replace the radiator A D of Fig. 5, so that for economicalreasons as much heat as possible is retained in the ovens or cellsthereof by applying a suitable non-conductor of heat partially around,as in Fig. 2, or completely around, as in Fig. 5.

Fig. 13 shows another diagram, in which all the winding D forms part ofthe energizing-circuit; but a portion of it D is shown closed on itselfby the conductor D The commercial article for domestic purposes is shownin Figs. 14 and 15. The oven, stove, or range is shown to consist of, anoutside frame or shell a of suitable materialsuch as sheet or cast iron,steel, brass, and the like. his aguard-railaround thesame. (Shown partlybroken away.) are controllingswitches for the various grates orcompartments, the terminals of the conductor being 0' c c.. C is agrouping-switch, or such switch adapted to control simultaneously allgrates or compartments and their circuits. d are grate-cover plates. 6 eare water-heaters. f is a controlling-valve for the water.

9 is a baking or roasting oven. 9 is the door. hare hinges for the door.70 is a broiler. Z is a non-inflammable wall for screening and retainingthe heat and of slow heat-conducting capacity. m is a special form ofwaterheater. n and 0 are communicating tubes for hot and cold water. 19p are central heating and ventilating holes. 7' are valves forcontrolling the different water-compartments. s are contact-blocks,and sa sliding contactblock.

In Fig. 14, on the top surface of the shell or of the oven there areshown five removable grate-cover plates at, arrayed in the same way asin coal-stoves; but in this case under each plate (Z is fixed aheater-box H, which is shown in Figs. 2, 3, 3, 3 and 3 and in section inFig. 15. Each grate is preferably independentof the other and each iscontrolled by a switch a, one of which is' shown per each cover-plate d.The heating-conductors D of the various separate compartments areconnected in parallel with one another to the source, as shown in Fig.4:, whiletho conductor of each grate or for each compartment may besubdivided, (see Fig. 9,) the subdivisions being connected in serieswith one another and provided with contact-terminals s s and slide 5 toenable a variable length to be placed in circuit with the source I. Thestove, which'is a combination of a number of grates and compartments, ofwhich nine are shown in Figs. 14: and 15, are all controlled by a singleswitch C on the right-hand side of the stove, While each singlecompartment or grate can be cut out of circuit by a special switch 0.The bake-oven 9 consists here of a concentrator, as in Figs. 1, 5, 7,8,or 13. To prevent quick radiation for the sake of economy, the grate,shell, or receptacle A, with the heating-conductor D, are togethersurrounded by a non-inflammable material of slow heat-conductingcapacity, such as asbestus, mica, slate, earthenware, fireclay, brick,&c., as indicated by Z, which represents panes or tiles, some of whichappear in front view, others in section. This compartment is controlledby a switch below, while the second switch 0 shown controls the grate ofthe broiler below it. In both compartments g and 7c the food to beheated is placed on perforated supports or grates G or surrounded bycompartments whose sides and bottom are perforated, so as to allow aquick communication of the hot air surrounding the food, while at thesame time the local retaining of the heat is effected by the heat-screenZ, which prevents an easy diffusion of the heat developed through theframe a, as is usually the case with coal or gas stoves. WVhere economyis a secondary consideration, the

, stove can evidently be used without the screening material Z, as shownby the compartment 70, in which the same is omitted. The terminals ofthe heating-conductor D, if a fixture, are connected to the switches cand C, passing through the casing ain an insulated manner by usinginsulating-bushings. On the other hand, if the grate or compartment isremovable-as, for instance, A of the oven g-then special terminalstaremounted in the insulating material Z or in an insulated manner, and onintroducing the frame or support A, with its conductor D,the heatermakes contact with the terminals t, including the heating winding in thecircuit. In the broiler 7r, theheating-conductors D are shown mounted ona non-inflammable block or substance adapted to radiate or reflect theheat upward, while almost no heat will penetrate the block II to findits .way through the frame a. e e are boilers in connection with thestove. The compartment 6 having a comparatively small heating-surface,the water contained therein will take a longer time to become heatedthan that in the spiral c below e. Both heating-chambers are connectedby a valve f, which is adapted to keep the water separate or toallow thequicklyheated water in the tube or spiral e to rise and the cooler waterof box 6 to descend, and in this manner to hasten the heating of thewhole quantity of water, while for quickly obtaining a quantity of hotwater e alone would be used. Both water-heaters are inclosed by aheat-screen Z, as shown in section.

I 30 the spiral In Fi 15 the spiral heater 6' as a whole is shown to besurrounded by the conductor D.

Fi 16 gives the grouping-switch of Fig. 14. in detail. In Fig. let thecommutator-like contact-pieces c' are the terminals of the conductors Dof the various heaters. The switch-lever C", as shown in Fig. 18, ispivoted centrally to those terminals at the point a", around which theslide 0" is movable by its arm B" and operated by the handle 61'.

I claim as my invention 1. In an electric heater, the combination of abox provided with a door normally closed and an electric conductor woundaround-and insulated from said box.

2. In an electric heater, the combination of a hollow mass of anysuitable material, an electric conductor surrounding the same andseparated therefrom, and means, such as a door, by which articles to beheated may be entered into said mass.

3. In an electric heater, a box having parallel sides, insulating andfire-proof angular strips placed upon the corners and lapping over thesaid sides, and bare metallic wire forming an electric conductor woundaround the same and upon the insulating-strips,leaving air-spacesbetween said box and said wire, a door being provided in one end of thebox.

4. In an electric heater, a box having parallel sides, insulating andfire-proof angular strips placed upon it and lapping over the sides,bare metallic wire forming an electric conductor wound around the sameand upon the insulating-strips, leaving air-spaces between said box andsaid wire, a door being provided in one end of the box, and a casing offire-brick or similar poor conductor of heat surrounding the above-namedelements.

5. An electric heater consisting of the combination of a perforated boxprovided with a door normally closed, an electric conductor wound aroundsaid box, and a uon-heat-conducting substance surrounding the aboveelements.

6. An electric heater consisting of the combination of a perforated box,an electric conductor wound around the same, a non-heatconductingsubstance surrounding the two above-named elements, and a door adaptedto close said box as well as that formed by said non-conductingsubstance.

7. In an electric heater, the combination of an external frame,partitions dividing the internal space into several compartments, aheating-conductor located in some or all of said compartments, a poorheat-conducting substance lining the walls of one or more of saidcompartments, supports in close proximity to one or more of saidheating-conductors, and means, such as doors, lids, or openings, foraccess to the compartments.

8. An electric heater consisting of the combination of a perforated boxopen at one end, an electric conductor wound around the same, anon-heat-conducting substance surrounding the two above-named elementsexcept at said open side, and a door adapted to close the spacesurrounded by said non-heat conductor.

9. I11 an electric heater, the combination of a metallic box, a primaryelectric conductor surrounding said box and insulated therefrom, and anindependent or secondary conductor closed upon itself and surroundingand insulated from said box.

10. In an electric heater, the combination of a metallic box and anelectric conductor surrounding and insulated therefrom andshortcircuited as to a portion of the length of said conductor.

11. I11 an electric heater, a box having parallel sides,insulating-strips placed upon said box, bare metallic wire forming anelectric conductor wound around the box and saidinsulating-strips,leaving air-spaces between itself andthe said box, adoor being provided in one end of the box, and a casing of firebrick orsimilar poor conductor of heat surrounding the above-named elements.

12. In an electric heater, the combination of an external frame a,partitions dividing the internal-space into several compartments, asupport for cooking utensils, and a heatingconductor located inproximity to said support, and the last two elements being inclosed inone or more of said compartments.

13. In an electric heater, the combination of a perforated support, ametallic conductor surrounding the same, and a hollow box with means,such as a door, for temporarily opening or closing the same, the saidbox surrounding the above-named elements.

14. In an electric heater, the combination of a perforated receptacle, ametallic conductor surrounding the same, a suitable casing for inclosingthe above-named elements, and means, such as a door or cover, foradmitting access to said receptacle.

15. An electric heater consisting of the combination of a perforatedreceptacle, a metallic conductor surrounding the same, a casingsurrounding the above elements and separated from said conductor by anairchamber, and a door or cover, for the purpose described.

10'. In an electric heater, the combination, with a perforated oven orsupport, of adjustable plates adapted to cover more or less of the sidesof said perforated oven or support.

17. In a heater for alternating, pulsating, or intermittent electriccurrents, the combination of a conductor carrying the said currentsupplied from any suitable source and a metallic or magnetic hollow coreadapted to allow air circulation through its body in inductive distanceto said conductor.

In testimony that I claim the foregoing as my invention I have signed myname, in presence of two witnesses, this 15th day of October, 1890.

LUDIVIG GUTMANN.

Witnesses:

SAMUEL WALLACE, J AS. J. MoAFEE.

